Modern buildings include sophisticated HVAC&R systems that control the building's interior environment and/or a system process. For example, the air conditioning component of a building HVAC&R system includes at least one compressor, and often several compressors, that operate in conjunction with condensers, evaporators, fans, and other refrigeration circuit components to dehumidify and cool the air circulating throughout the building's interior. Ordinarily, each item of building equipment includes an electronic control panel that permits an operator to activate, deactivate, or adjust the speed or other operating parameter of the building equipment. The electronic control panel is often mounted directly on the equipment, but may alternatively be placed in proximity to the equipment at a location more easily accessible to the operator.
Increasingly, items of building equipment are being networked through building automation systems (“BAS”) to permit monitoring and limited control of the equipment by technicians and operators at on-site locations, such as a control room, that are several feet to several hundred feet away from the operating equipment. This allows operators to obtain data from the equipment and to adjust operating parameters of networked equipment accordingly. One component of such a BAS includes a Programmable Logic Controller (“PLC”) that includes a back plane for connecting building equipment control modules to the PLC, and further includes simple “ladder logic” for controlling the modules. Due to their logic structure, PLCs, as opposed to microprocessors, can only handle a very limited number of logic functions, and can only perform a very limited number of calculations or other tasks simultaneously. The priority task of known PLCs is to provide data gathering for monitoring purposes, and known PLC-type controllers inherently require attachment to other items of equipment and to a local computer network in order to function in a BAS. The BAS is in essence an intelligent breaker box that turns equipment on or off at scheduled times and upon the happening of certain events. For example, in the case of a fire, a building fire system component would detect fire and tell the BAS to shut off lights and other building equipment that may encourage the spread of fire. Moreover, PLCs operating in a BAS are required to respond to a large number of systems, and must adhere to inflexible communication protocols by which the connected systems can connect and poll with, as well as different protocols for communicating with and controlling the controlled equipment. These requirements, combined with the limited logic capability and slow processing speed of known PLCs, make PLCs a poor choice for flexible and intelligent control of building equipment.
Accordingly, what is needed is a non-PLC controller having a microprocessor that permits fast and accurate gathering, processing, and storage of data from both standalone and BAS-networked building equipment, and also having an embedded web server that allows a plurality of authorized users, whether local or remote, to simultaneously access and view data, and to adjust operation of the equipment.
Furthermore, in typical known embedded controllers, only about twenty percent (20%) of the software program is dedicated to control of the equipment. The remaining eighty percent (80%) is dedicated to monitoring and permitting interaction with users, such as at a human-machine interface device (“HMI”). Accordingly, what is needed is a controller that separates the program code for monitoring from the program code for equipment control in a manner that is efficient yet invisible to users accessing the controller through a HMI.